The objectives of this grant are to develop better discrimination of liver graft rejection (differentiating rejection from obstruction, hepatitis, and other causes of hepatic malfunction), to evaluate the role of humoral antibodies and cell-mediated immunity in rejection, to study the influence of the native liver disease on the outcome, to treat selected cases of inborn errors of metabolism with liver replacement, to determine further the optimal conditions of hepatic graft revascularization, to improve liver preservation techniques, and to seriously investigate in animals any of the aforementioned questions when applicable. The criteria to judge progress in various areas include patient suvival after liver replacement, liver function in the postoperative period, the quality of life, the histopathologic findings in the transplants from serial biopsies, and the nature of the duct system as visualized by cholangiography during the postoperative period.